fn main() {
    let a = 1u32;
    println!("{}", a);

    let uint = ();

    let b = a; // 拷贝赋值

    println!("{}", b);
    println!("{}", a);

    //
    let mut c = 1;
    c = 2;
    c += 1;
    println!("1 c={}", c);
    {
        let c = 100;
        println!("2 c={}", c);
    }
    println!("3 c={}", c);
    //
    
}
